This card can win you games. Such a plot twister. Kill 0/x minions or set up 1/7 for Big Game Hunter (sounds a bit like a waste of two excellent cards though). You can also use it to protect your low health attacking units: hit with 6/2 and turn it into 2/6 so it can live to fight another day. A truly great card!

If the targeted minion is later silenced, regardless of what its Attack and Health were at the time of the silence effect, it will revert to its original stats. I had a damaged Chillwind Yeti turned into a 1/4 by this; a silence brought it back to 4/5.

How to break the game with the Gurubashi Berserker, the Crazy Alchemist, any "deal 1-2 damage to any minion/character" cards and/or taunt.

Summon your Gurubashi Berserker, once you are confident you can play this combo. Use any abilities which read "deal 1 damage" or "deal 2 damage" on this card you possibly can. If or when your Gurubashi Berserker's attack exceeds 7 and reached it's maximum potential on your turn, play the Crazy Alchemist to swap your Gurubashi's attack and health. Now, you have an even more bullet-spongey Gurubashi Berserker to grind for more +3s. Once your Gurubashi Berserker has traded enough blows with your opponent, feel free to play another Crazy Alchemist.

Extra: If you have Dream or Pandaren Brewmasters, you can return the Crazy Alchemist to your hand in order to use it's battlecry on the Gurubashi Berserker again. That makes a total of 9 uses of the battlecry.

Optimally, without healing or playing your 3 alchemists more than once, you can grind your Gurubashi Berserker to a +172 Attack minion. If you use Dream or Brewmasters, this can climb into the tens of thousands, without even mentioning some deck's abilities to heal. No one in their right mind would let such a berserker stay on your side of the field, though, nor would anyone neglect it's potential to insta-kill an enemy hero.